In the House, 31 Democrats rebuffed their leadership on the expiring Bush-era tax cuts, signing a letter calling for temporary extension of all the breaks and signaling a possible impasse in Washington's bid to deal with the thorny political problem.

The letter provided the most dramatic sign yet of Democrat jitters over voting for the Obama administration's plan to extend current tax levels for middle-class earners—families making less than $250,000—while allowing taxes to rise for higher earners starting January.

House Democratic leaders had hoped to use the tax cuts as a rallying cry in the run-up to the election, casting Republicans who favor extending all the breaks as obstructionists and allies of the rich. Instead, the party now faces long odds in passing its tax plan before the November elections. The 31 Democrats, plus House Republicans, come close to forming a majority in that chamber.

"In my head, I know it's not good policy to raise taxes in a recession," said Rep. Michael McMahon (D., N.Y.), one of the members who signed this week's letter. "And in my heart, I know it's bad politics to raise taxes at any time."

Tea Party Names on the Ballot

Republican candidate for New York governor Carl Paladino Associated Press

Republicans, widely expected to see big gains this November, were scrambling to mend their own fences, between the party establishment and the candidates that challenged it during the primary season. Party leaders were stunned on Tuesday when tea-party favorite Christine O'Donnell won the Delaware Senate primary over longtime Rep. Mike Castle, the centrist Republican backed by party leaders.

Trying to unify the party, the head of the Republican Senate campaign committee, Sen. John Cornyn, made clear he supports Ms. O'Donnell and said he would send a contribution to her campaign. But party officials said there were no plans to invest in any significant way by funding TV ads to support her race.

Ms. O'Donnell's win fueled a growing debate about the GOP's November prospects. Some strategists argued that grass-roots activists, while motivated largely by anger at government spending and the Democrats' new health-care law, had touched off an ideological cleansing that could damage the party in November and beyond.

ENLARGE

Ms. O'Donnell has taken heat for a series of revelations about her personal finances and positions that some Republicans argue are too rightward for the state, and her victory was seen by many in both parties as boosting Democrats' prospects in the race.

"You can't make forward progress without a majority," said Republican strategist Jim Barnett, who worked on the Castle race and managed an unsuccessful Senate primary bid by another centrist Republican backed by party leaders, former Rep. Rob Simmons of Connecticut. "Conservatives in the Senate will remain in the wilderness until and unless we can elect Republicans in all parts of the country."

But Sen. Jim DeMint (R., S.C.), a leader in the push for more conservative candidates, argued that the party was improving its chances by embracing ideas that most Americans cherish. "I don't think this is about purity at all," he said. "This is the right way to get to a big-tent Republican Party."

The disputes in both parties capped a long, tumultuous primary season that saw an unusually high number of incumbents lose to political newcomers, as the conservative tea-party movement exerted influence in a number of key races.

While virtually all polls suggest Democrats will feel the brunt of voter anger on Nov. 2, the GOP felt the heaviest impact of the tea-party movement in the primaries. In all, the National Republican Senatorial Committee saw a total of eight of its chosen candidates fall to outsider insurgents this year, including two sitting senators, Lisa Murkowski of Alaska and Robert Bennett of Utah. The Democrats lost a sitting senator as well, party-switching Arlen Specter of Pennsylvania.

In the general election, many trends seem favorable for Republicans, including a huge upsurge in Republican primary voters and enthusiasm and a low approval rating for President Barack Obama. But leaders in both parties remain uneasy amid polls that suggest neither party is viewed favorably by the majority of voters, and that is causing a rethink of strategies for both.

For Democrats, much of the recent debate has centered on the pending expiration of the Bush-era tax cuts. An impasse on a bill to extend them for the middle-class before the election would leave incumbents vulnerable to criticism by Republicans that they are effectively letting taxes rise.

But a number of incumbent Democrats in both House and Senate worry their exposure is higher if they vote for the administration's proposal, and can be tagged with explicitly approving tax increases.

Speaker Nancy Pelosi's office didn't immediately respond to a request for comment on the letter. Ms. Pelosi has led her caucus decisively since the election of Mr. Obama, but her grip over her members may be loosening under the intensifying pressure of a difficult campaign season for Democrats.

House leaders tried in recent days to use polling data to show lawmakers that voters support the administration's plan to extend only the middle-class breaks. But many Democrats remain unpersuaded.

Democratic Rep. Glenn Nye of Virginia said in a statement Wednesday that many of the taxpayers in the top two brackets are "successful small business owners" who should have "the support they need to thrive."

A spokesman for Republican leader John Boehner said the letter showed that some Democrats are waking up to the unpopularity of the administration's solution. "A growing bipartisan chorus is listening to the American people, who know the last thing we need in a struggling economy is a tax hike on small business," said spokesman Michael Steel.

But he said the signers should force the leadership to allow an up-or-down vote on extension of all the tax breaks. "Until they do that, this reeks of election-year posturing," he added.

Both parties were also reevaluating how to spend their limited resources in the field. Their discussions suggested the battle for the Senate would be most fiercely fought in states such as Missouri and Colorado, where Democrats already are advertising, and Kentucky, where the Republicans' Senate committee has just started its first ad run. Republicans began advertising in Colorado Wednesday night.

Washington State is shaping up to be a firewall for Democrats as they try to hold the Senate. But party officials acknowledge their North Dakota Senate seat is gone, and they are likely to cut losses in Arkansas and Indiana soon, officials said. They will give Ohio Lt. Gov. Lee Fisher two more weeks to show he can make a race of the open Senate seat.

"I can just say we will spend our money where we can win," said Sen. Robert Menendez (D, N.J.), chairman of the Democratic Senatorial Campaign Committee. "We will have a majority in November. It's a question of how robust we can make it."

A senior Republican official, meanwhile, said his party's first priority is "to make sure we get to 218 in the House," and thus a majority, adding that the Senate was a decidedly secondary priority.

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